The invention relates to a device for establishing or releasing a coupling between an adjustment ring, which can be rotated on a base element by way of a detent mechanism and is provided with an adjustment shaft for optical elements, and a cylindrical index ring, which is inserted between the adjustment ring and the base element so as to rotate in relation to an index mark provided on the base element.
On telescopic sights, it is known to vary the elevation of the aiming point on a reticle provided in the optical path of the telescopic sight by way of an adjustment ring that can be latched onto the outside of the telescopic sight on a base element. The elevation is dependent upon the target distance and the ammunition fired at the aiming point. In the case of a telescopic sight mounted on a barrel, the elevation is thus typically set on the adjustment ring by a person skilled in the art for a standardized target distance and customarily used ammunition, and is zeroed with the aid of an index ring coupled to the adjustment ring in relation to an index mark provided on the base element.
The detent positions of the adjustment ring correspond to a standardized, incrementally variable target distance. The individual detent positions can be felt and heard by a clicking sound, so that the shooter is also able to discern the changed target distance even in the dark.
The aforementioned index ring is coupled to the adjustment ring, so that the change in the detent positions can also be read optically via the change in the setting of the index ring in relation to the index mark, and the adjustment ring can be returned to the zeroed starting position when the use of the firearm has been completed.
The elevation of the reticle must likewise be adapted when a change in the ammunition type occurs. Via the typical trajectory of the ammunition type, this adaptation likewise affects the target distance which was set by way of the adjustment ring and to which the zero position of the index ring must be adapted when the different ammunition type continues to be used.
It is known to effectuate the coupling between the adjustment ring and the index ring by way of mutual interlocking. The interlocking mechanism can be released by manually pulling the adjustment ring or with the aid of a tool, and can be re-established in a different relative position. Due to the engagement in the teeth, only discrete changes in the relative position are possible, which influence the accuracy of the setting of the reticle to the standardized target distance.
It is therefore the object of the invention to be able to set, in particular continuously, the coupling between the adjustment ring and the index ring in a device of the type mentioned above, without using a special tool.